This invention relates generally to air purifiers and, more particularly, to a portable room air purifier providing filter use information.
There is an ever increasing need to provide clean air environments both at home and in the work place. Especially in urban areas where pollutant levels are in excess of those recommended for good health, it is necessary to upgrade living and work environments by removing harmful contaminants from the air.
Airborne pollutants contribute to respiratory infections and illnesses and can be especially damaging to individuals with respiratory problems including allergies or from Asthma. Symptoms of high pollutant levels are burning eyes, nose and throat irritations, headaches, dizziness, coughing and sneezing. Individuals are constantly inhaling particles of dust, smoke, pollen, mold spores, acids, bacteria, viruses, animal hair, soot, and harmful chemicals.
In an effort to provide some relief from airborne pollutants, many offices and homes utilize central filtering systems to remove particles from the air. Unfortunately, such centralized systems, which are economically available, do not remove more than approximately 80-85% of the particles in the air and are only effective on particles which are approximately one micron or larger.
The need to have substantially purified air has resulted in the creation of special filter elements which are defined as HEPA filters. HEPA stands for High Efficiency Particulate Air filters which by, federal standard, are filters with a minimum efficiency of 99.9%. The industry defines HEPA filters as those filters which are efficient in removing 99.97% of airborne particles of a size of 0.3 micron or larger.
Although such HEPA filter elements were originally designed for use in ultra clean environments including laboratories, electronic and biologically clean rooms, hospitals and the like, such filters have been used in portable structures which may be utilized in individual room environments. U.S. Pat. No. 5,435,817 discloses such a portable room air purifier having a housing in which a filter element is positioned so as to be intermediate an air inlet and an air outlet and wherein a fan is driven by a motor so as to urge air inwardly through the inlet and discharge the air towards the outlet. The portable room air purifier further includes at least one scroll which is oriented so as to direct air from the fan generally tangently with respect to the axis of the fan through a scroll discharge opening. A deflector is mounted in spaced relationship with respect to the discharge opening and the deflector tapers inwardly relative to the scroll to thereby define an open passageway through which air is directed as it is exhausted through the air outlet. The disclosed filter structure provides improved uniform filtered air distribution with a relatively compact device. However, a need exists for even more efficient portable room air purifiers.
Clogging of filter elements is one factor which adversely impacts the efficiency of an air purifier. Consequently, timely replacement of filter elements is critical to prolonged efficient operation. That problem is addressed in U.S. Pat. No. 4,629,482 which discloses a portable air purifier providing an audible indication of a clogged filter condition. However, the disclosed indicator system exhibits certain undesirable characteristics such as annoying noise generation and unreliable performance. Also known are battery operated timer systems for indicating a clogged filter condition. Such systems time continuously and, therefore, can be unreliable when the device experiences periods of inactivity.
The object of this invention, therefore, is to provide a portable room air purifier with improved operating efficiency over an extended period of use.